In 2012, NASA sponsored research and design efforts related to an RF (Radio Frequency) channel using a microstrip (SMA launching excitation) with a perforated ground plane for a cryogenic application. Teams from various Universities and NASA participated in this research, design and prototype effort. A device was eventually designed and was able to achieve isolation levels of about 30 dB over a relatively narrow frequency range and perform at temperatures of 297 K and 77 K.
What is needed is an RF transmission structure for cryogenic applications with a larger frequency band of operation, a better impedance match and improved channel-to-channel isolation.